Fluoro- and cyano-substituted 1,4-phenylene-bis(hydrocarbylmalononitriles)and process of preparation

ABSTRACT

COMPOUNDS OF THE FORMULA   1,4-DI(R4-CH(-R3)-C(-R1)(-R2)-C(-CN)2-),2-A,3-B,5-E,6-D-   BENZENE   IN WHICH R1, R2, R3 AND R4 ARE HYDROGEN OR HYDROCARBYL OF 1-10 CARBON ATOMS FREE OF OLEFINIC OR ACETYLENIC UNSATURATION AND WHEREIN A, B, D AND E ARE HYDROGEN, FLUORINE OR A CYANO GROUP WITH THE PROVISO THAT NO MORE THAN TWO OF A, B, D AND E ARE HYDROGEN, CAN BE MADE BY REACTION OF THE APPROPRIATE SUBSTITUTED MALONONITRILE WITH A COMPOUND   1,4-DI(X-),2-A,3-B,5-E,6-D-BENZENE   IN WHICH X IS HALOGEN, IN THE PRESENCE OF AN ALKALI METAL, ALKALINE EARTH METAL, OR LOWER ALKOXIDES THEREOF. THE COMPOUNDS ARE INTERMEDIATES FOR THE PREPARATION OF SUBSTITUTED TETRACYANOQUINODIMETHANS USEFUL AS DYESTUFFS AND FOR THE PREPARATION OF CHARGE TRANSFER COMPLEXES OF TETRACYANOQUINODIMETHANS ALSO USEFUL DYESTUFFS AND ANTISTATIC AGENTS.

3,739,008 FLUORO- AND CYANO-SUBSTITUTED 1,4-PHENYLENE-BIS(HYDROCARBYLMALONO- NITRILES) AND PROCESS OF PREPARATIONElmore Louis Martin, Wilmington, Del., assignor to E. I. du Pont deNemours and Company, Wilmington, Del. No Drawing. Continuation-impart ofapplication Ser. No. 664,315, Aug. 30, 1967, which is acontinuation-in-part of application Ser. No. 514,385, Dec. 16, 1965.This application Sept. 22, 1970, Ser. No. 74,466

Int. Cl. C07c 49/62, 121/02, 121/66 US. Cl..260-465 G 6 Claims ABSTRACTOF THE DISCLOSURE Compounds of the formua in which R R R and R arehydrogen or hydrocarbyl of 1-10 carbon atoms free of olefinic oracetylenic unsaturation and wherein A, B, D and E are hydrogen, fluorineor a cyano group with the proviso that no more than two of A, B, D and Eare hydrogen, can be made by reaction of the appropriate substitutedmalononitrile with a compound in which X is halogen, in the presence ofan alkali metal, alkaline earth metal, or lower alkoxides thereof. Thecompounds are intermediates for the preparation of substitutedtetracyanoquinodimethans useful as dyestufis and for the preparation ofcharge transfer complexes of tetracyanoquinodimethans also usefuldyestuffs and antistatic agents.

RELATED APPLICATIONS This application is a continuation-in-part ofapplication Ser. No. 664,315 filed Aug. 30, 1967 now US. 3,558,- 671which is a continuation-in-part of application Ser. No. 514,385 filedDec. 16, 1965 now US. 3,504,001.

FIELD OF THE INVENTION This invention relates to a new class of chemicalcompounds, namely fluoroand cyano-substituted1,4-phenylene-bis(hydrocarbylmalononitriles) SUMMARY OF THE INVENTIONThe products of this invention have the formula wherein A, B, D and Eare the same or diiferent and are hydrogen, fluorine or a cyano group(-CN) with at least two of A, B, D and E being other than hydrogen, andR R R and R are hydrocarbyl of l-lO carbon atoms free of olefinic oracetylenic unsaturation.

DETAILED DESCRIPTION OF THE INVENTION The products of this invention areintermediates for the preparation of1,4-bis(dicyanomethylene)-substituted cyclohexadienes of the formula A BQN CG QN "United States Patent 01 lice Patented June 12, 1973 Thesubstituted 1,4-bis(dicyanomethylene)cyclohexadienes of Formula I, orthe substituted tetracyanoquinodimethans as they are alternativelycalled and which can be repersented by the symbols STCNQ for brevity,can be prepared by the following three-step process. In the first step,a substituted malononitrile of the formula where R R R and R are thesame or difierent and are as define above, is reacted with an alkali oralkaline earth metal, alkali metal or alkaline earth metal hydride, oralkali metal or alkaline earth metal lower alkoxide and a substitutedbenzene of the formula D E wherein the Xs are fluorine, chlorine,bromine, or iodine and A, B, D, and E are as defined previously, in thepresence of an inert, anhydrous, aprotic liquid reaction medium, e.g.,ethylene glycol dimethyl ether (glyme), tetrahydrofuran, diethyl ether,dioxane, dimethyl sulfoxide, N,N-dimethylformamide, tetramethylenesulfone, etc., at a temperature of 0 to 0, preferably at 10-15 C., andthe resulting solution is then heated to 4090 C. in an inert atmosphere,e.g., in an atmosphere of nitrogen, for several hours, e.g., l-24 hours.After cooling, the reaction mixture is diluted with a large volume ofwater and the resulting solid reaction product is filtered from thereaction mixture. This product has the general formula This product,which is the precursor for the substituted tetracyanoquinodimethan andwhich can be termed STCNQ(P) for brevity, can be purified byconventional methods, e.g., by washing with suitable diluents and bycrystallization from suitable solvents.

Specific alkaline materials suitable for reaction With themonosubstituted malononitriles in the above-described process includemetallic lithium, sodium and potassium; lithium, potassium and sodiumhydrides; the lower alkoxides of lithium, sodium and potassium; andbutyllithium.

The term hydrocarbyl is used in conventional sense to refer to a rdicalor group derived from a hydrocarbon radical by removal or replacement ofone atom of hydrogen.

Hydrocarbyl group free of aliphatic (i.e. ethylenic or acetylenicunsaturation) therefore includes alkyl groups, cycloalkyl groups, arylgroups and aralkyl groups.

Examples of alkyl groups include methyl, ethyl, npropyl, isopropyl,n-butyl, t-butyl, n-octyl, 2-ethylhexyl and n-decyl groups.

Examples of cycloaliphatic groups include cyclohexyl,4-methylcyclohexyl, 3-n-propylcyclohexyl, cyclopentyl, 3-methylcyclopentyl and the like.

Examples of of aryl groups include phenyl; 4-methylphenyl;3-methylphenyl; 4-(t-butyl)phenyl; 3,4-dimethylphenyl and naphthylgroups.

An example of an aralkyl group is the benzyl group.

The preferred hydrocarbyl groups are lower alkyl groups, particularlymethyl groups and phenyl groups.

In the second step of the process, the STCNQ(P) is heated to an elevatedtemperature to decompose it to the corresponding substituted1,4-bis(dicyanomethyl)benzene, or alternatively the substituteddihydrotetracyanoquinodimethan, which can be termed STCNQHQ for brevity,of the formula (1N D E (IN (v1) and an olefin. The temperature requiredto decompose the quinodimethan precursor to the dihydroquinodimethan isdependent on the thermal stability of the precursor. The temperatureshould be sufiiciently high to cause the precursor to decompose to thequinodimethan and an olefin at a practical rate but not so high as tocause excessive decomposition of the resulting dihydroquinodimethan. Asuitable temperature range is ZOO-300 C., with 220-260 C. beingpreferable. When a reaction temperature in the upper portion of theoperable range is employed, reaction takes place almost instantaneously.In the preferred temperature range with a batch process on a laboratoryscale, reaction times of 1-5 minutes are sufiicient. Shorter reactiontimes can be used at higher temperatures and are preferred, especiallywhen the process is conducted on a continuous basis. Longer reactiontimes are required when the decomposition is carried out in the lowerportion of the above operable range.

The decomposition of the STCNQ precursor can be carried out in anyreaction medium that does not react with the precursor or the resultingdihydroquinodimethan. Suitable reaction media include hydrocarbons,ethers, esters, amides, lactones, lactams, ketones, alcohols,chlorinated hydrocarbons, and the like. The preferred reaction media arethe aromatic hydrocarbons, aromatic ketones, aromatic ethers, and alkylesters of carboxylic acids, e.g., biphenyl, diphenylmethane,benzophenone, phenyl ether, dibenzofuran, dimethyl phthalate, and thelike. The reaction medium selected must be one that boils at or abovethe decomposition temperature of the reactant when the reaction iscarried out at atmospheric pressure. However, lower boiling reactionmedia can be used if the decomposition is carried out undersuperatmospheric pressure. The reaction can also be carried out in thevapor phase either at atmospheric or reduced pressures. Optionally acarrier material such as nitrogen, helium, benzene, etc., may also beused in the process. Also a heat transfer material such as glass beads,solid polytetrafluoroethylene resin, and the like, may also be used. Theratio of the STCNQ precursor to the reaction medium employed is notcritical, and the reaction can be carried out under heterogeneous orhomogeneous conditions. However, it is preferred that the precursor beessentially completely soluble in the reaction medium at thedecomposition temperature. In general, 1-10 parts of STCNQ precursor to100 parts of reaction medium is preferred.

The substituted dihydroquinodimethan, STCNQH can be isolated from thereaction medium by any convenient method. For example, it can beextracted from the reaction medium by the use of an aqueous solution ofan alkali metal hydroxide, carbonate, or bicarbonate, and precipitatedfrom the resulting aqueous solution by acidification. The reactionmedium may be removed by distillation under reduced pressure and theresidual dihydroquinodimethan purified by crystallization or converteddirectly to the quinodimethan as described in further detail below. Thereaction medium can also be cooled and the reaction product isolated byfiltration.

The cyanoand fluoro-substituted dihydroquinodimethans form salts withquaternary ammonium halides which are useful as dyes. Thus, the coloredquaternary ammonium salts of these STNCQH s can be used to dye variousfabrics, e.g., nylon, wool, silk, etc.

In the third step of the process, the substituteddihydrotetracyanoquinodimethan can be oxidized to the substitutccltetracyanoquinodimethan by t a ment with a convenient oxidizing agentsuch as chlorine, bromine, nitric acid (usually in admixture withanother strong mineral acid such as hydrochloric acid) at ordinary ormoderately elevated temperatures, e.g., 25-100 C. Such oxidationprocedures are described in US. Pat. 3,115,506. The resultingsubstituted tetracyanoquinodimethan, STCNQ, can be isolated andpurified, if desired, by conventional methods. For example, the STCNQcan be purified by washing and by crystallization from a suitableorganic solvent, e.g., methylene chloride.

As indicated previously, the STCNQH need not be isolated from itsreaction solution prior to oxidation. If desired, the neutralizedaqueous alkaline extract of the decomposition mixture can be useddirecty in the third, or oxidation, step.

The substituted malononitriles of Formula III and the substitutedbenzenes of Formula -IV used as starting materials in preparing thecompounds of this invention are themselves known compounds or can beprepared by well-known methods. See U.S. Pats. 3,166,583 and 3,179,- 692for detailed procedures.

The 1,4-bis(dicyanomethylene)-substituted cyclohexadienes, or as theycan be alternatively named, fluoroand/ or cyano substituted 7,7,8,8tetracyanoquinodimethans, form charge-transfer compounds with Lewisbases broadly, including specifically organic and organo-inorganic Lewisbases. The charge-transfer compounds of the substitutedtetracyanoquinodimethans (STCNQ, for brevity) with Lewis bases range indegree of charge-transfer from those of true complex structure to thosewhere actual and complete charge-transfer exists in the groundelectrical state. Compounds of the last-mentioned type constituteso-called anion-radical salts wherein at least one molecule of STCNQcarries at least one transferred electron, and accordingly a negativeelectronic charge, and at least one molecule of the Lewis base componentwill have donated at least one electron to the STCNQ component and willaccordingly have an electron deficiency, and, therefore, a positiveelectronic charge.

The charge transfer compounds of STCNQ with Lewis acids are genericallydescribed by the formula M+ (STCNQ, )s(STONQ,)b (XI) wherein STCNQ, asis so throughout this specification, represents generically the variousfiuorineand cyanosubstituted TCNQS as defined hereinbefore; n is theformal positive charge on the cation M, and is also the number ofunpaired electron. This formula includes charge-transfer compounds ofthe type in which no neutral species are present and charge-transfergompounds in which up to three neutral species are comined.

As shown in the above formulae, the STCNQ species collectivelyassociated with a cation containing a number of unpaired electrons equalto the formal charge on the cation. These unpaired electrons arebelieved to be distributed over all the STCNQ species whetherrepresented as formally neutral or formally containing an unpairedelectron. That is, the unpaired electrons are believed to be notlocalized on a single carbon atom or even on a single STCNQ group. As isconventional, the above classical formulae are intended to representsuch non-classical structures.

Lewis bases which, with STCNQ, form the necessary second component forforming the ch rg -transfer compounds of STCNQ are well known to thechemical art (see G. N. Lewis, J. Franklin Institute 226, 293 (1938) andfollowing papers by Lewis and several coauthors). Broadly speaking, theLewis base is, by definition, simply a molecule, the structure orconfiguration of which, electronically speaking, is so arranged that themolecule is capable of donating one or more electrons to a moleculewhich has an electron-deficient structure. Many and varied electrondonor compounds are known. Well-recognized classes of Lewis bases, andmany specific examples of such bases, are listed in US. Pat. 3,162,641.Any of these particular Lewis bases are equally operable in forming thecharge-transfer complexes of the STCNQs of the present invention.

The charge-transfer compounds in which the STCNQ moiety is presentwholly in ion-radical form, i.e., chargetransfer compounds of formula X,are best described as simple salts of STCNQ anion-radicals, i.e.,

STCNQ The cations in these simple charge-transfer anion-radical saltsare equally Well organic or inorganic cations. Physically, the membersof this class of charge-transfer compounds are distinguished byelectrical resistivities of the order of magnitude of 1x10 ohm-cm. orgreater. Salts of STCNQ with organic cations exhibit especially highelectrical resistivities of the order of 1X10 to 1 10 ohm-cm. Thesesalts can be used to dye nylon, wool and silk because of the presence ofbasic groups in these materials that form salts with the charge-transfercompounds.

These simple salts can be prepared directly by simple interactionbetween a suitable source of the desired cation and the substitutedtetracyanoquinodimethan, or preferably by metathetic reaction between asuitable source of a cation and a convenient source of the STCNQanionradical. Thus, alkali metal salts of the substitutedtetracyanoquinodimethans are easily prepared directly from a suitablealkali metal salt, e.g., sodium iodide, and the fiuoroorcyano-substituted tetracyanoquinodimethan in an inert reaction medium,e.g., anhydrous acetonitrile, at ordinary or moderately elevatedtemperatures, e.g., at the reflux temperature of the reaction mixture.The alkali metal STCNQ? salt formed is insoluble in the cold reactionmixture, e.g., at -10 C., and can be isolated by conventional means,e.g., by filtration followed by Washing and drying. This procedure isdescribed by L. R. Melby et al., J. Am. Chem. Soc. 84, 3374 (1965), forthe preparation of TGNQF' salts.

The simple alkali metal salts of the STCNQ amonradical are convenientlyused as starting materials for metathetical reactions with other cationsalts to form salts of STCNQ with other than alkali metals, e.g., withalkaline earth or heavy metals and with organic cations, e.g.,quaternary ammonium and cyclic amine salts. In these metatheticalreactions at source of the desired cation and a suitable reaction mediumare selected so that the desired salt of the ST CNQ,T precipitates fromthe reaction mixture. Thus, for example, a solution of in a mixture ofacetonitrile and Water is treated with an excess of aqueoustetramethylammonium chloride whereupon crystals of the desireda)4N+(STCNQ*) precipitate from the reaction mixture.

6 The second class of charge-transfer compounds of the fiuoroandcyano-substituted tetracyanoquinodimethans, i.e., those of Formula XI,contain, in addition to the requisite stoichiometric amount of toachieve electrical neutrality, additional combined proportions ofneutral STCNQ. This class of charge-transfer compounds can be preparedunder temperature and concentration conditions and, in general, in thesame solvent systems, as discussed above for the simple anion-radicalsalts. In most instances, these salts involving the combined neutralSTCNQ will be more readily obtained with organic cations. With suchcations, these salts can be obtained by reaction of a salt of thedesired organic cation with the substituted tetracyanoquinodimethan,e.g., by reaction of quinolinium with additional STCNQ at ordinary ormoderately elevated temperatures. After the reaction is completed, thereaction mixture can be cooled, e.g., to O10 C., whereby the crystals ofthe STCNQ anion-radical salt containing combined neutral STCNQprecipitate from the reaction mixture. The crystals can be isolated fromthe reaction mixture by conventional means, e.g., by filtration, etc.

The charge-transfer compounds are deeply colored; consequently they areuseful for various purposes. Thus, the crystals of the charge-transfercompounds can be used as pearlescent materials in otherwise colorlessplastics, or as pearlescent pigment materials in decorative lacquers andplastic solutions, and for dyeing nylon, wool and silk. The products ofthis invention are illustrated in the following examples, which shouldnot however be construed as fully delineating the scope of thediscovery.

EXAMPLE I Part A-Preparation of 2,3,5,6-tetrafluoro-1,4-bis-(amethylbenzyldicyanomethyl)benzene om ON 1113 INON on- HaCo-CHC n-o rr AN? N To a stirred suspension of 15.8 parts ofsodium hydride in 200 parts of anhydrous ethylene glycol dimethyl ether(glyme) was added dropwise at 1015 C. a solution of 112 parts ofa-methylbenzylmalononitrile in parts of glyme. To the resultinghomogeneous solution was added 56 parts of hexafiuorobenzene and thereaction mixture was refluxed under an atmosphere of nitrogen for aperiod of 8 hours. The reaction mixture was cooled and diluted with alarge volume of cold water. The 2,3,5,6 tetrafluoro 1,4 bis(ocmethylbenzyldicyanomethyl)benzene was collected, washed first withwater, then methanol, and finally with ether and gave 69 parts of anearly colorless product. Crystallization from methylene chloride gavecolorless crystals, M.P. 241243 C. with decomposition.

Analysis.Calcd. for C H N F (percent): C, 69.13; H, 3.72; N, 11.52; F,15.62. Found (percent): C, 68.98; H, 3.68; N, 11.66; F, 15.33.

Part B-Preparation of 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethan (TCNQF A mixture of one part of2,3,5,6-tetrafluoro-1,4-bis-(amethylbenzyldicyanomethyl)benzene in 20parts of Dowtherm A (a commercial mixture of diphenyl and diphenyl etherboiling at 255 C. at 760 mm. pressure) was heated to reflux rapidly andmaintained at reflux for one minute. The resulting solution was cooledrapidly to 40 C. and diluted with an equal volume of ether. Theresulting solution was extracted with about 50 parts of a 5% potassiumhydroxide solution, the aqueous layer was neutralized with 6 Nhydrochloric acid and bromine water was added until a positive test forfree bromine was obtained. The resulting yellow precipitate wascollected, washed with water and crystallized from methylene chloride togive yellow crystals of 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethan, M.P. 295-300" C. with decomposition.

Analysis.-Calcd. for C N F (percent): C, 52.20; H, 0.00; :N, 20.29; F,27.52. Found (percent): C, 52.03; H, 0.00; N, 20.17; F, 27.43.

EXAMPLE II Part A-Preparation of2,3,5,6-tetrafluoro-1,4-bis-(tertbutyldicyanomethyl) benzene To amechanically stirred suspension of 28.8 parts of sodium hydride in 300parts of anhydrous glyme was added dropwise at l0-15 C. a solution of150 parts of tertbutylmalononitrile in 150 parts of glyme. To theresulting homogeneous solution was added 93 parts of hexafluorobenzeneand the reaction mixture was refluxed for 7 hours, during which time acolorless solid separated. The reaction mixture was diluted with water,the crude 2,3,5,6-tetrafluoro-1,4-bis(tert-butyldicyanomethyl) benzenewas collected, washed in turn with water, methanol and ether. The yieldof nearly colorless crystals was 157 parts. Crystallization from a largevolume of acetone gave colorless crystals, M.P. about 285 C. withdecomposition.

Analysis.-Calcd. for C H N F (percent): C, 61.53; H, 4.65; N, 14.35; F,19.47. Found (percent): C, 61.58; H, 4.61; N, 14.47; F, 19.44.

8 Part BPreparation of 2,3,5,6-tetrafluoro-1,4-bis-(dicyanomethyl(benzene (TCNQF H To parts of diphenyl ether heated toreflux was added rapidly with vigorous stirring 3.9 parts of 2,3,5,6-tetrafluoro-1,4-bis (tert-butyldicyanomethyl )-benzene and the resultingsolution was refluxed for 3.5 minutes. After cooling rapidly to 40 C.,the reaction mixture was diluted with an equal volume of ether andextracted with 50 parts of 4% potassium hydroxide solution followed bythree extractions with 15 parts of 2.5% potassium hydroxide solution.The combined aqueous layers were acidified with 6 N hydrochloric acid,the precipitate was collected, washed with water and crystallized frommethylene chloride. The colorless crystals of2,3,5,6-tetrafluoro-l,4-bis(dicyanomethyl)benzene melted withdecomposition at 27 6300 C.

Analysis.Calcd. for C H N F (percent): C, 51.81; H, 0.72; N, 20.14; F,27.32. Found (percent): C, 51.88; H, 1.02; N; 19.84; F, 27.18.

CN CH3 F F CH3 ON I I I HaC-(F-(E CH3 ON I CN A mixture of one part of2,3,5,6 tetrafluoro-1,4-bis (tert-butyldicyanomethyl)benzene and 20parts of diphenyl ether was heated at reflux temperature for 3 minutes.The resulting solution was cooled rapidly to 40 C., then diluted with anequal volume of ether and extracted with 50 parts of 5% potassiumhydroxide solution. The aqueous layer was acidified with 6 Nhydrochloric acid and bromine water was added until a test for freebromine was obtained. The yellow precipitate was collected, washed withwater and crystallized from methylene chloride to give yellow crystalsof TCNQF M.P. 295300 C. with decomposition. The infrared spectrum of theproduct was identical with that of the sample of TCNQE; described inExample 1.

EXAMPLE III Preparation of7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethan To 350 parts ofdiphenyl ether heated to reflux and stirred mechanically was addedrapidly in one portion 7.8 parts of2,3,5,6-tetrafiuoro-1,4-bis(tert-butyldicyanomethyl)benzene and thesolution was refluxed for 3 minutes. The solution was cooled rapidly to40 C., an equal volume of ether was added followed by the addition of100 parts of a 4% sodium bicarbonate solution. The aqueous layer wasseparated, and the organic layer was extracted an additional three timeswith 33 parts of a 1% sodium bicarbonate solution. To the combinedaqueous solution was added 5 parts of acetic acid and 7.5 parts ofpotassium acetate followed by the addition of bromine water until apositive test for free bromine was obtained. The yellow precipitate wascollected, washed with water and 10 the filter cake was dissolved inabout 3,300 parts of methtion gave crystals of thebistetrapropylammonium salt of ylene chloride. The aqueous layer wasseparated, the or- 2,5 dicyano-1,4-bis(dicyanomethyl)benzene melting atganic layer was treated with a small amount of decoloriz- 226-228" C.with decomposition. This compound dyes ing charcoal and dried byanhydrous magnesium sulfate. nylon, silk, and wool dilferent shades ofred.

The resulting clear yellow filtrate was concentrated until 5 a thickpaste of yellow crystals of 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethan was obtained. The crystals Analysis.-Calcd.for C H N (percent): C, 72.80; H, 9.32; N, 17.88. Found (percent): C,73.11; H, 8.94; N,

were collected, washed with a small volume of methylene chloride, andfinally Washed with ether. The yield was 4.7 P t CPrep atin 0f 2,,7,7,8,8-hexacyanoquinodiparts (85%) of yellow crystals. methan(TCNQ(CN) EXAMPLE IV To 750 parts of diphenyl ether maintained at 225 C.Part A--Preparation of 2,5-dicyano-1,4-bis(tert-butyldias added rapidlyin one portion 18.4 g. of 2,5-dicyanocyanomethyl)benzene 1,4bis(tert-butyldicyanomethyl)benzene. After 3 minutes, the mixture wascooled rapidly to 40 C., diluted with CH ON an equal volume of ether and300 parts of a 4% sodium I 3 I bicarbonate solution was added. Theorganic layer was 2HaC-CCH ZNaH -Q extracted with two portions of 150parts of 1% sodium bi- Hs E carbonate and the combined aqueous solutionswere fil- C tered. The deep red filtrate was neutralized with 6 N hy- ONdrochloric acid and bromine water was added until a (IDES I Q E Epositive test for free bromine was obtained. The pre- H3C-C-C CCCH3cipitate was collected, washed with water and air-dried. CH3 A I CH3Crystallization from large volume of acetonitrile gave brownish-yellowcrystalls of 2,5,7,7,8,8-hexacyanoquino- To a stirred suspension of 16.8parts of sodium hydride dlmethan: in 200 parts of glyme was added atl0-15 C. a solution Analysls-calcdfor 14 2 6 (P of 85.4 parts oftert-butylmalononitrile in 100 parts of 2 N, Found (P C, 6594; N, glyme.To the resulting solution was added 59 parts of 2,5dichloroterephthalonitrile and the mixture was re- EXAMPLE V fluxedunder an atmosphere of nitrogen for 20 hours, dur- Part APreparation of2,5-dicyano-3,6-difluoro-1,4-bising which time colorless crystalsseparated. The reaction (tert-butylidcyanomethyl)benzene mixture wasconcentrated to a thick paste under reduced F CN pressure. Water wasadded and the precipitate was col- CH; CN 1 lected and washed in turnwith water, methanol, and +2NaH ether. The nearly colorless2,5-dicyano-1,4-bis-(tertbutyl- 1 N dicyanomethyl)benzene Weighed 86parts (78% of 3 J; F theory) and crystallization from methylene chloridegave F ON colorless crystals melting with decomposition at 265 C. CH CN1 0 0 Analysis.Calcd. for C H N (percent): C, 71.72; l H, 5.47; N,22.81. Found (percent): C, 71.39; H, 5.31; l

CH3 CN CN CH3 N, 22.58. NC F Part BPreparation ofbis-tetrapropylammonium salt of To a stirred suspension of 5.3 parts ofsodium hydride 2,5-dicyano-1,4-bis(dicyanomethyl)benzene in parts ofglyme was added dropwise at l015 C.

ON ON CH3 (IN I (IJN (EH: (IN I C|3N i@ i- (.7113 ON ON CH3 ON ON ON ONPart C 1! ON CN ON ([)N N C\ /CN (uloolfi +-o fi(oaum o =o ON ON NO ONON N To 1500 parts of diphenyl ether heated at 225 C. was added rapidlyin one portion 18.4 parts of 2,5-dicyanoa solution of 26.8 parts oftert-butylmalononitrile in 100 1,4-bis(tert-butyldicyanomethyl)benzeneand the mixture parts of glyme. To the resulting solution was added 20stirred for 3 minutes. The resulting solution was cooled parts oftetrafiuoroterephthalonitrile d h reaction i rapidly to 40 C., dilutedwith an equal volume of ether ture was stirred for 2 hours at 40 C. andat 50 C. for 2 followed by addition of 1000 parts of 1% sodiumbicarhours, during which time a white solid separated. The rebonatesolution. The organic layer was extracted with two action mixture wasdiluted with water and the filter cake portions of 150 parts of 1%sodium bicarbonate soluwas Washed in turn with water, methanol and etherto tion, and the combined aqueous solutions were filtered. To give 34parts of light yellow crystals of 2,5-dicyano-3,6-

the resulting deep red filtrate was added a concentrated 7O difiuoro 1,4bis(tert butyldicyanomethyl)benzene. aqueous solution of 50 parts oftetrapropylammonium Crystallization from acetone gave colorlesscrystals, M.P. iodide and the deep purple salt was collected, washedabout 250 C. with decomposition.

with cold water and crystallized from aqueous metha- Analysis.Calcd. forC H N F (percent): C, 65.34;

1101. The yield of reddish-violet crystals, melting at 2l9- H, 4.48; N,20.78. Found (percent): C, 65.20; H, 4.60; 225 C. with decomposition,was 53 parts. Recrystalliza- N, 20.79.

11 Part B-Preparation of his tetrapropylammonium salt of 2,5 dicyano 3,6difiuoro 1,4 bis(dicyanomethyl)benzene ON F ON J: ON IN To 150 parts ofdiphenyl ether at 225 C. was added one part of2,5-dicyano-3,6-difiuoro-l,4-bis(tert-butyldicyanomethyl)benzene and thesolution was stirred at 225 C. for one minute. The reaction mixture wascooled rapidly to 40 C., was diluted with an equal volume of ether and35 parts of a 1% sodium bicarbonate solution was added. The organiclayer was extracted with two portions of 10 parts of 1% sodiumbicarbonate, the combined filtrates were filtered and a saturatedsolution of 2 parts of tetrapropylammonium iodide was added. Theresulting deep red precipitate was collected, washed with water andcrystallized twice from aqueous methanol to give deep purple crystals ofthe bis-tetrapropylammonium salt of 2,5dicyano-3,6-difluoro-1,4bis(dicyanomethyl)benzene. This compound dyednylon, silk and wool shades of red.

Analysis.-Calcd. for C H N F (percent): C, 68.85; H, 8.52; N, 16.90.Found (percent): c, 68.56; H, 8.50; N, 17.23.

Part C-Preparation of 2,5,7,7,8,8-hexacyano-3,6-

To 150 parts of diphenyl ether at 225 C. was added rapidly one part of2,5-dicyano-3,6-difluoro-1,4-bis(tertbutyldicyanomethyl)benzene and themixture was stirred at 225 C. for one minute. The reaction mixture wascooled rapidly to 40 C., diluted with an equal volume of diethyl etherand 35 parts of a 1% potassium bicarbonate solution was added. Theorganic layer was extracted with two portions of 10 parts each of 1%potassium bicarbonate solution, the combined aqueous layers werefiltered and 50 parts of solid potassium chloride was added. Afterstirring for a few minutes the nearly black dipotassium salt of 2,5dicyano-3,6-difluoro-1,4-bis(dicyanomethyl)benzene was collected, washedfirst with a small volume of 10% potassium chloride solution, then witha small volume of potassium chloride solution and finally with anhydrousether. After drying at 5 C. and 25 mm. pressure over phosphoruspentoxide, the yield was 0.85 part. To a solution of 5 parts of silvernitrate in parts of water was added a filtered solution of the abovedipotassium salt in 100 parts of water. The nearly black silver salt wascollected and washed in turn with water, methanol and anhydrous ether.After drying, the 1.15 parts of nearly black powder was suspended inabout 25 parts of anhydrous acetonitrile and a solution of 0.33 part ofiodine in about 30 parts of anhydrous acetonitrile was added. Theprecipitated silver iodine was filtered off and washed with acetonitrileuntil colorless. Concentration of the filtrate under reduced pressure toa small volume gave 0.5 part of brown-yellow microscopic crystals.Crystallization of 0.1 part from about 500 parts of ethylene dichloridegave 0.05 part of 2,5,7,7,8,8-hexacyano 3,6 difiuoroquinodimethane asbrownish yellow crystals.

Analysis.-Calcd. for C N F (percent): C, 57.94; H, 0.00; N, 28.96. Found(percent): C, 57.86; H, 0.00; N, 28.76.

Addition of molecular silver to a solution of the quinodimethan inacetonitrile results in immediate formation of the magenta-coloreddianion of 2,5-dicyano-3,6difluoro-1,4-bis(dicyanomethyl)benzene.

The fluoroand cyano-substituted tetracyanoquinodimethans also possessthe important adpantage over the useful as dyes, for instance, as dyesfor gasoline, as well as dyes for coloring textiles, threads, films, andthe like, by conventional dyeing techniques.

The fluoroand cyano-substituted tetracyanoquinodimethans also possessthe important advantage over the hitherto known tetracyanoquinodimethan,and its hydrocarbon-substituted derivatives, of being considerably lessresistant to reduction. This enables them to be employed in manyapplications involving oxidizing conditions. This greater resistance ofthe dianions derived from the substituted tetracyanoquinodimethans ofthis invention to oxidation is shown in Table TV which gives theequilibrium potentials of fluoroand cyano-substituted TCNQs compared tothe corresponding values of unsubstituted TCNQ and certainhydrocarbon-substituted TCNQs. These equilibrium potentials weremeasured by chronopotentiometric experiments in acetonitrile containingtetraethylammonium perchlorate using working and auxiliary electrodes ofplatinum. The reference electrode was Ag-/AgNO (10- m.) in acetonitrile.The values obtained in these measurements were then converted bystandard conversion factor to redox potentials vs. the saturated calomelelectrode. All of these processes obey the Nernst equation.

TABLE I Redox potentials of certain tetracyanoquinodimethans Redoxpotentials, in volts, vs.

Both the simple charge-transfer compounds and those having combinedneutral species, having intermediate conductivities are useful inapplications such as antistatic agents for fibers and in somesemi-conductor applications.

The charge-transfer compounds of the fiuoroand cyano-substitutedtetracyanoquinodimethans possess unexpected properties compared to thecorresponding charge-transfer compounds of tetracyanoquinodimethan andalkyl-substituted tetracyanoquinodimethans. For ex- 13 ample,tetrafluorotetracyanoquinodimethan is more soluble thantetracyanoquinodimethan itself in acetonitrile. As many apparentlywidely diiferent embodiments of this invention may be made withoutdeparting from the spirit and scope thereof, it is to be understood thatthis invention is not limited to the specific embodiments thereof exceptas defined in the appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

I claim: 1. A compound having the formula R1 ON A B CN R R C( J l m R-(J-H (3N D E (IN Erik-R I l R4 in which R R R and R each individuallyis hydrogen or hydrocarbyl of 1-10 carbon atoms free of olefinic oracetylenic unsaturation, and A, B, D and E are hydrogen, fluorine orcyano with the previso that no more than two of A, B, D and E arehydrogen.

2. Compound of claim 1 wherein R and R are each methyl and R and R areeach hydrogen.

3. Compound of claim 2 wherein A, B, D and E are each fluorine.

4. Compound of claim 2 wherein A and E are each cyano and B and D arehydrogen.

5. Compound of claim 2. wherein A and E are each fluorine and B and Dare cyano.

6. A process for preparing a compound of claim 1 which comprisescontacting and reacting a substituted malononitrile having the formulain which R R R and R each individually is hydrogen or hydrocarbyl of1-10 carbon atoms free of olefinic or acetylenic unsaturation with acompound having the formula wherein A, B, D and E are hydrogen, fluorineor cyano with the proviso that no more than two of A, B, D and E arehydrogen, and in which X is halogen, and with alkali metal, alkalineearth metal, alkali metal hydride, alkali metal lower alkoxide oralkaline earth metal lower alkoxide in an anhydrous inert aproticorganic solvent at a temperature of 0 C. to 100 C. in an inertatmosphere, and continuing the reaction at 40 to for 1 to 24 hours.

References Cited UNITED STATES PATENTS OTHER REFERENCES Bergstrom etal., J. Am. Chem. Soc., vol. 67, pp. 2152 to 2154 (1945).

FLOYD -D. 'I-HGEL, Primary Examiner US. Cl. X.R.

44-59; l1713=8.-8 N, 141; 20812; 26037 NP, 396 N, 430, 464, 465 E, 465H, 465.8 R

